Synthesis and Investigation of Number of Anchoring and Spacer Effect in Triphenylamine-Based Organic Dyes for p-Type Dye Sensitized Solar Cells

Three novel dyes comprising a triphenylamine donor, different numbers of cyanine conjugated spacer and carboxylic acid anchor groups were synthesized and employed as photosensitizers in p-type dye-sensitized solar cells (p-DSSC). The absorbance of the dyes in solution was red shifted and the oxidation potential gradually increased with increasing the number of spacers and anchoring groups. It was found that introduction of three carboxylic acid groups into the triphenylamine (TPA) unit (TC3) exhibited better photovoltaic performance. An increasing number of spacer and anchoring group resulted in higher current-density, photo-voltage and higher efficiency. The charge transporting ability is enhanced with increasing anchoring groups, as evidenced from electrochemical impedance analysis.